1. Field of the Invention
The present invention relates to a probe apparatus and more particularly to a probe apparatus having an improved probe card exchange mechanism.
2. Description of the Related Art
There has been known a probe apparatus for examining electrical characteristics of a plurality of IC chips formed on a semiconductor wafer. This kind of probe apparatus comprises a probe card having probes, that is, contact elements provided to correspond to electrode pads of each IC chip. The probe card is attached to an insert ring supported by the head plate of an apparatus casing. A work table, which is movable in horizontal directions (X, Y directions) and a vertical direction (Z direction) and which is rotatable in a .theta. direction, is provided below the insert ring, that is, below the probe card.
At the time of examining, the work table is moved in the X, Y and .theta. directions such that the electrode pads of each IC chip provided on the wafer are opposite to the corresponding probes of the probe card. Then, the work table is moved up such that the electrode pads of the IC chip come in electrically contact with the probes. These operations are performed every IC chip or every group consisting of a plurality of IC chips. In a state that the electrode pads of each IC chip are in electrical contact with the probes, an electrical signal is sent to the IC chip, and the electrical characteristic of the IC chip is examined.
Moreover, in order to provide a mark to an IC chip, which has been recognized to be defective by the examination, a marking mechanism is provided. An ink applying section of the marking mechanism, that is, a pen is provided at a marking area separated from a probing area in which the probe card is arranged. At the time of marking, the work table on which the wafer is mounted is moved such that an IC chip, which has been recognized to be defective, is opposite to the pen of the marking mechanism. Then, ink is dropped from the pen, and the mark is applied to the defective IC chip.
The probe card is formed to examine only one kind of IC chip. Due to this, the probe card has to be exchanged for a new one in accordance with the kinds of IC chips formed on the wafer. In recent years, various kinds of IC chips have been manufactured in order to fulfill various functions of electronic equipments. Due to this, the exchange of the probe card has become frequent. As a method for exchanging the probe card, there are used a method for automatically exchanging the probe card and a method for manually exchanging the probe card.
In the case of the automatic exchanging method, a plurality of probe cards are prepared in a stock chamber of the probe apparatus in advance. The probe cards are automatically picked up from the stock chamber by an automatic exchanger incorporated into the probe apparatus.
In the case of the manual exchanging method, a head plate, which is supported by a apparatus casing and having a probe card attached thereto, is swung up by an operator from the front side of the probe apparatus to a back side by a predetermined angle to be opened. Then, in a state that the head plate is kept open and inclined, the probe card is exchanged. In this case, the probe card is exchanged as being attached to a card holder. Then, the head plate is swung again to be returned to the usable position.
In the case of the automatic exchanging method, the probe card can be automatically exchanged without using the operator's hand. However, the automatic exchanger is mechanically complex, and is expensive. Also, the maintenance of the automatic exchanger becomes complicated. Also, several kinds of probe cards, which are not urgently needed, must be stocked in addition to a probe card, which are currently used. For these reasons, the cost of the probe apparatus becomes high.
In the case of the manual exchanging method, since it is unnecessary to stock extra probe cards, and no automatic exchanger is provided, the cost of the probe apparatus becomes low. However, every time when the probe card is exchanged, the operator must open and close the head plate and detach and attach the probe card with a card holder. In recent years, the plurality of IC chips are examined at the same time in accordance with demands for a high-speed examination. As a result, the diameter of the probe card and that of the card holder are enlarged. Also, the probe card and the card holder are increased in the weight. Due to this, in the case of the manual exchanging operation of the probe card, much effort and attention have been needed.
As other problems, various considerations must be taken in providing the marking mechanism. One is that the marking mechanism must be provided in order not to hinder the probing operation. The other is that the maintenance of the marking mechanism must be made easy. For these reasons, the marking area is provided to be separated from the probing area, thereby causing the size of the probe apparatus to be enlarged.